Software Testing - Smoke Testing

Smoke Testing

Smoke testing, also known as build verification testing, is a preliminary level of software testing performed to ensure that the most critical and basic functionalities of an application work correctly after a new build or update. It is a shallow but wide form of testing that checks whether the application is stable enough for further, more detailed testing.

The main goal of smoke testing is to verify that the essential features of the software are functioning as expected and that the build is not broken. If the build fails smoke testing, it is rejected, and the development team fixes the issues before proceeding to deeper testing stages.

Purpose of Smoke Testing

  1. Verify Build Stability: Ensures that the latest code build is stable and can proceed to further testing.

  2. Detect Major Defects Early: Catches critical failures right after new code integration.

  3. Save Time and Effort: Prevents QA teams from wasting resources on testing an unstable build.

  4. Quick Feedback Loop: Provides immediate feedback to developers after build deployment.

  5. Confidence Building: Confirms that basic system functionality is intact before continuing with detailed tests.

When Smoke Testing Is Performed
Smoke testing is carried out whenever a new build or version of the software is released. It is typically performed:

  • After integrating new features or fixes.

  • Before starting detailed testing such as regression or system testing.

  • As part of continuous integration (CI) pipelines to validate new code merges.

Characteristics of Smoke Testing

  • Broad but Shallow: Covers major functionalities without going into deep details.

  • Quick to Execute: Designed to run in a short time, often within minutes.

  • Performed Frequently: Applied after every new build or code deployment.

  • Automated or Manual: Can be automated for CI/CD pipelines or done manually for smaller builds.

  • Gatekeeper Testing: Determines whether a build is stable enough to proceed to further testing.

Smoke Testing Process

  1. Build Deployment: The development team delivers a new software build for testing.

  2. Smoke Test Suite Creation: QA engineers prepare a small set of test cases covering key functionalities.

  3. Test Execution: Execute the smoke tests manually or through automation tools.

  4. Result Evaluation: If the build passes all smoke tests, it moves to deeper testing phases; if not, it is rejected.

  5. Defect Reporting: Log critical issues found during testing and notify the development team for fixes.

Example in Real Terms
Imagine an online food delivery application. After a new update, smoke testing checks whether users can:

  • Open the app successfully.

  • Log in with valid credentials.

  • Search for restaurants.

  • Add an item to the cart.

  • Proceed to the payment page.

If any of these essential features fail, the build is rejected for further testing until fixed.

Tools Commonly Used for Smoke Testing

  • Automation Tools: Selenium, Cypress, QTP/UFT.

  • CI/CD Integration Tools: Jenkins, GitHub Actions, GitLab CI.

  • Test Management: Jira, TestRail, Zephyr.

Best Practices for Smoke Testing

  1. Identify Critical Paths: Focus on the core features that define system usability.

  2. Automate When Possible: Use automation to quickly verify builds in CI/CD pipelines.

  3. Maintain a Minimal Test Suite: Keep the smoke test set small but comprehensive enough to check major functions.

  4. Perform After Every Build: Make smoke testing a mandatory step in every release cycle.

  5. Communicate Results Quickly: Provide immediate feedback to the development team for quick fixes.

  6. Use Stable Test Data: Ensure consistency across builds by using reliable input data.

Difference Between Smoke Testing and Sanity Testing

Aspect Smoke Testing Sanity Testing
Purpose Checks basic system stability after a new build. Verifies that new features or bug fixes work correctly.
Scope Broad and shallow. Narrow and deep.
Performed By Usually QA or automation team. Usually QA after receiving a stable build.
Automation Level Often automated. Often manual.
Build Rejection Build is rejected if it fails. Build may still proceed for limited testing.

Benefits of Smoke Testing

  • Detects showstopper bugs early in the cycle.

  • Saves time and effort by avoiding testing unstable builds.

  • Improves build quality and confidence.

  • Provides quick feedback to development teams.

  • Reduces risk of deeper testing on faulty software.

Smoke testing acts as a first line of defense in the software testing process. It verifies that the essential features of an application function correctly before detailed testing begins. By ensuring build stability early on, smoke testing helps maintain efficiency, saves resources, and accelerates the overall development and release process.